This herb prevents attacks and eases the pain

What it is Butterbur (Petasites hybridus) has exotic stalks of purple flowers that bloom before its elephantine leaves appear.

What folk medicine says Herbalists in the Middle Ages used butterbur's roots to treat fevers and plague. Seventeenth-century medical literature cites its use for headaches, asthma, allergies, and coughs.

What we know Research suggests that the plant contains compounds that prevent blood vessel inflammation—a possible migraine trigger. In a 2000 study, German researchers gave 58 migraine sufferers either 50 mg of butterbur extract or placebo pills twice a day. After 3 months, the butterbur takers had approximately 50% fewer migraines; the placebo group saw about a 10% decrease. No side effects were reported.

What research shows In a recent study, German and American researchers gave adult migraine sufferers either a 75-mg dose or a placebo twice a day. After 4 months, researchers found that butterbur reduced migraines by 48%; the placebo reduced them by 26%. (Migraines often respond to a placebo; on average, about a third of patients respond to sugar pills.)

A new German study of 108 children with recurrent migraines showed similar results: 10- to 17-year-olds got 50 mg of butterbur twice a day; 6- to 9-year-olds took half as much. After 4 months, both groups reported less pain, and 77% had halved the number of migraines they usually got.

What to buy Petadolex is the supplement used in the studies. Avoid home-brewed tonics—they can be toxic.

Dose: Follow instructions on the package. Cost: $41.50 for 50 pills at migraineaid.com.